title: Impact of geocoding methods on associations between long-term exposure to urban air pollution and lung function.
abstract: BACKGROUND
  Errors in address geocodes may affect estimates of the effects of air pollution on health.
  
  
  OBJECTIVE
  We investigated the impact of four geocoding techniques on the association between urban air pollution estimated with a fine-scale (10 m × 10 m) dispersion model and lung function in adults.
  
  
  METHODS
  We measured forced expiratory volume in 1 sec (FEV1) and forced vital capacity (FVC) in 354 adult residents of Grenoble, France, who were participants in two well-characterized studies, the Epidemiological Study on the Genetics and Environment on Asthma (EGEA) and the European Community Respiratory Health Survey (ECRHS). Home addresses were geocoded using individual building matching as the reference approach and three spatial interpolation approaches. We used a dispersion model to estimate mean PM10 and nitrogen dioxide concentrations at each participant's address during the 12 months preceding their lung function measurements. Associations between exposures and lung function parameters were adjusted for individual confounders and same-day exposure to air pollutants. The geocoding techniques were compared with regard to geographical distances between coordinates, exposure estimates, and associations between the estimated exposures and health effects.
  
  
  RESULTS
  Median distances between coordinates estimated using the building matching and the three interpolation techniques were 26.4, 27.9, and 35.6 m. Compared with exposure estimates based on building matching, PM10 concentrations based on the three interpolation techniques tended to be overestimated. When building matching was used to estimate exposures, a one-interquartile range increase in PM10 (3.0 μg/m3) was associated with a 3.72-point decrease in FVC% predicted (95% CI: -0.56, -6.88) and a 3.86-point decrease in FEV1% predicted (95% CI: -0.14, -3.24). The magnitude of associations decreased when other geocoding approaches were used [e.g., for FVC% predicted -2.81 (95% CI: -0.26, -5.35) using NavTEQ, or 2.08 (95% CI -4.63, 0.47, p = 0.11) using Google Maps].
  
  
  CONCLUSIONS
  Our findings suggest that the choice of geocoding technique may influence estimated health effects when air pollution exposures are estimated using a fine-scale exposure model.
authors.affiliation: Inserm (Institut National de la Santé et de la Recherche Médicale), CESP (Centre de recherche en Épidémiologie et Santé des Populations), U1018, Respiratory and Environmental Epidemiology Team, Villejuif, France.
authors.forename: Bénédicte
authors.initials: B
authors.lastname: Jacquemin
authors.forename: Johanna
authors.initials: J
authors.lastname: Lepeule
authors.forename: Anne
authors.initials: A
authors.lastname: Boudier
authors.forename: Caroline
authors.initials: C
authors.lastname: Arnould
authors.forename: Meriem
authors.initials: M
authors.lastname: Benmerad
authors.forename: Claire
authors.initials: C
authors.lastname: Chappaz
authors.forename: Joane
authors.initials: J
authors.lastname: Ferran
authors.forename: Francine
authors.initials: F
authors.lastname: Kauffmann
authors.forename: Xavier
authors.initials: X
authors.lastname: Morelli
authors.forename: Isabelle
authors.initials: I
authors.lastname: Pin
authors.forename: Christophe
authors.initials: C
authors.lastname: Pison
authors.forename: Isabelle
authors.initials: I
authors.lastname: Rios
authors.forename: Sofia
authors.initials: S
authors.lastname: Temam
authors.forename: Nino
authors.initials: N
authors.lastname: Künzli
authors.forename: Rémy
authors.initials: R
authors.lastname: Slama
authors.forename: Valérie
authors.initials: V
authors.lastname: Siroux
mesh_terms: D000328:Adult; D000397:Air Pollution / Q000009:adverse effects*; D002947:Cities; D004781:Environmental Exposure / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D005541:Forced Expiratory Volume / Q000187:drug effects*; D005602:France; D062305:Geographic Mapping; D006801:Humans; D008962:Models, Theoretical; D014797:Vital Capacity / Q000187:drug effects*